(1) Field of the Invention
The present invention relates in general to a method and apparatus for forming a section beam and in particular to a new and novel yarn sheet transfer apparatus for such a system.
(2) Description of the Prior Art
Section beams are generally formed by a batch-type process. Individual warp yarn packages first are mounted within a creel with typically between 400 to 700 individual warp yarn packages being required. Next, warp yarn from each package is withdrawn under uniform tension and parallelized by means of a comb or Vee-reed to form a yarn sheet. Maintaining uniform yarn tension is well-known to be a key factor in preventing end breaks during the section warping process.
After parallelization, the yarn sheet is wound upon a take-up spool by a warping machine to form the section beam. When the spool is filled, the yarn sheet is cut and taped and the completed section beam is removed. Additional section beams are wound until the required yardage of a particular warp yarn is accumulated.
The yardage of a particular warp style so produced has traditionally been greatly in excess of the yards of yarn available on a typical creeled package. Thus, in order to maintain continuous warping for as long as possible, "running package" and "transfer package" positions are provided for each warp end on the creel. This allows the yarn from the running end to be fed to the warper while the transfer package position is tied to the trailing end of the running package so that when the running package is depleted, yarn is withdrawn from the transfer package. Then, the prior running package position may be recreeled as the transfer package position. This results in the creel having twice as many package positions as there are warp yarn ends.
When a yarn sheet of a different color, pattern, weight, or count is required, the warping machine must be stopped until all the individual warp yarn packages are replaced, which may take several hours. With the trend to smaller lots of specialty fabrics and, the increase of actual spool winding speeds to greater than 1000 yds/min., considerable attention has been paid to creel design with the object of reducing recreeling time and, at the same time, maintaining uniform tension on the individual warp yarns. One such system, illustrated in U.S. Pat. No. 3,441,991, utilizes creel "trucks" in which one or more creels are movably mounted on wheels or tracks with respect to a fixed warping machine. An entire creel truck is replaced with another creel truck having the desired number and type of yarn packages. Still another such system is a "duplicated" creel in which two fixed creels are employed side-by-side and the warping machine is movably mounted on rails so that it can be moved laterally from one creel to another. A variation of the duplicated creel is shown in German Pat. No. DE-3,105,461 in which a pair of fixed creels are located at the front and rear sides of a warping machine which is mounted on a turntable so that it can be rotated from one creel to another.
Certain disadvantages become apparent with such designs. First, either the creel or the warping machine must be specially built to be movable with respect to one another, requiring a substantial capital investment. Second, the steps of withdrawing the warp yarn from the individual packages under uniform tension and parallelizing to form the yarn sheet cannot be performed until the replacement creel and warping machine have been aligned with respect to one another.
Thus, it has become desirable to develop a yarn sheet transfer system for a section beam warping machine that will permit the quick change from one creel half to another without the need for special creels or warping machines while at the same time permitting the concurrent withdrawing of the warp under uniform tension and parallelization of the yarn sheet prior to the alignment of the replacement creel with respect to the warping machine.